fix: don't parse Dell FW release date if it's 0000-00-00T00:00:00Z

[krish-nvidia]

Newer iDRAC firmware (7.30.10.50+) returns 0000-00-00T00:00:00Z as a placeholder ReleaseDate for firmware entries with no known release date. This is an invalid RFC 3339 date (month 00 is out of range) and causes downstream parsing failures. The existing quirk already stripped the legacy 00:00:00Z form from older iDRAC versions; this extends it to also strip the newer zeroed-out datetime form.

 level=INFO span_id=0x614a682534e41a1d msg="Failed to explore <bmc-ip>:443: Error while performing Redfish request:
 context: firmware inventories; json error: the \'month\' component could not be parsed: None (response code: None) (state:
 Ready)" error="Error while performing Redfish request: context: firmware inventories; json error: the \'month\' component
 could not be parsed: None (response code: None)" location="crates/api/src/site_explorer/mod.rs:1538